Method of inspecting tip of atomic force microscope and method of manufacturing semiconductor device

ABSTRACT

A method of operating an atomic force microscope (AFM) is provided. The method includes inspecting a sample by using the AFM and inspecting a tip of a probe of the AFM by using a characterization sample. The characterization sample includes a first characterization pattern that includes a line and space pattern of a first height, a second characterization pattern that includes a line and space pattern of a second height that is lower than the first height, and a third characterization pattern that includes a line and space pattern of a third height that is lower than the second height, and includes a rough surface.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority under 35 U.S.C. § 119to Korean Patent Application No. 10-2021-0184327, filed on Dec. 21,2021, in the Korean Intellectual Property Office, the disclosure ofwhich is incorporated by reference herein in its entirety.

BACKGROUND

Aspects of the inventive concept relate to a method of inspecting a tipof an atomic force microscope (AFM) and a method of manufacturing asemiconductor device.

A tip of a probe of an AFM may be evaluated by scanning acharacterization sample by the tip. The tip of the probe may beevaluated by generating a tip model based on an image of thecharacterization sample generated by using the tip of the probe of theAFM. A characterization sample may include a surface structure suitablefor inferring a tip state when imaging is performed by using a probe. Arepresentative characterization sample includes a surface patterned in aline and space shape.

Evaluation of a tip may elaborate a three-dimensional tip model bycontinuously analyzing local peaks of a surface topographic image. Agradient most quickly away from each peak in all directions may bemeasured at the peak, and minimum sharpness of a tip may be determinedfrom the gradient. A premise of this modeling is that data of an imagegenerated by measurement using an AFM cannot have a sharper gradientthan a gradient of a tip. When a process of determining sharpness of atip is recursively performed on a plurality of local peaks, if there isa sharper gradient than gradients discovered at all peaks previouslyanalyzed, a tip model is updated to a new and sharper tip estimationvalue.

SUMMARY

Aspects of the inventive concept provide a method of operating an atomicforce microscope (AFM) with improved reliability and a method ofmanufacturing a semiconductor device.

According to an aspect of the inventive concept, there is provided amethod of operating an AFM. The method includes: inspecting a sample byusing the AFM; and inspecting a tip of a probe of the AFM by using acharacterization sample, wherein the characterization sample includes: afirst characterization pattern that includes a line and space pattern ofa first height; a second characterization pattern that includes a lineand space pattern of a second height that is lower than the firstheight; and a third characterization pattern that includes a line andspace pattern of a third height that is lower than the second height,and includes a rough surface.

According to another aspect of the inventive concept, there is provideda method of operating an AFM. The method includes: inspecting a sampleby using the AFM; generating, based on the inspecting, a scanned sampleimage including one or more abnormalities; inspecting a tip of a probeof the AFM by using a characterization sample to determine if the tip isnormal or abnormal; determining that the sample is abnormal if the tipof the AFM is determined to be normal; and replacing the tip of the AFMif the tip of the AFM is determined to be abnormal.

According to another aspect of the inventive concept, there is provideda method of manufacturing a semiconductor device. The method includes:forming active patterns separated from each other on a substrate, byanisotropically etching the substrate; forming a device isolation layerin a device isolation trench that is a space between the activepatterns; forming gate trenches separated from each other in a firstdirection that is parallel to an upper surface of the substrate,extending in a second direction that is parallel to the upper surface ofthe substrate and perpendicular to the first direction, and partiallypenetrating into the device isolation layer and the active patterns;forming a dielectric material layer partially filling the gate trench;forming a gate conductive material layer filling the gate trench;forming a gate conductive pattern in the gate trench by planarizing thedielectric material layer and the gate conductive material layer;forming a gate mask on the gate conductive pattern; forming firstimpurity regions and second impurity regions by doping upper parts ofthe active patterns; forming a capping layer and a first interlayerinsulating layer covering the gate mask, the first impurity regions, andthe second impurity regions; etching the capping layer and the firstinterlayer insulating layer to form a groove through which the firstimpurity regions are exposed; inspecting any one of the device isolationtrench, the dielectric material layer, the gate conductive pattern, andthe groove by using an AFM; inspecting a tip of a probe of the AFM byusing a characterization sample to determine if the tip is normal orabnormal; and determining that any one of the device isolation trench,the dielectric material layer, the gate conductive pattern, and thegroove is abnormal, based in part on whether the tip is determined to benormal.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the inventive concept will be more clearly understoodfrom the following detailed description taken in conjunction with theaccompanying drawings in which:

FIG. 1 schematically illustrates an atomic force microscope (AFM);

FIG. 2 is a flowchart for describing a method of operating an AFM,according to example embodiments;

FIG. 3A illustrates a first characterization pattern of acharacterization sample;

FIG. 3B illustrates an image generated by scanning the firstcharacterization pattern of the characterization sample;

FIG. 3C illustrates a damaged tip of an AFM;

FIG. 4 illustrates a second characterization pattern of acharacterization sample;

FIG. 5 illustrates a third characterization pattern of acharacterization sample;

FIGS. 6A to 6C show changes in an image of a sample according tosharpness of an end portion of a tip of an AFM;

FIG. 7 is a flowchart for describing a method of manufacturing asemiconductor device, according to example embodiments; and

FIGS. 8A, 8B, 9A, 9B, 10A, 10B, and 11 to 20 are top views andcross-sectional views for describing the method of manufacturing asemiconductor device, according to example embodiments.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments of the inventive concept are described indetail with reference to the accompanying drawings. Like referencenumerals in the drawings denote like elements, and a repeateddescription thereof is omitted.

FIG. 1 schematically illustrates an atomic force microscope (AFM) 100capable of performing an inspection method, according to exampleembodiments.

Referring to FIG. 1 , the AFM 100 may include a sample support 110, aprobe 120, a scanner 130, a laser device 140, a photodetector 150, aprocessor 160, and a controller 170.

The AFM 100 may sense a surface of a sample S with sensitivity of anindividual atom level on the surface of the sample S. The AFM 100 mayinspect the surface of the sample S by detecting a Van der Waals forceor an electrostatic force between a tip 121 of the probe 120 and thesample S. The AFM 100 may inspect the sample S by horizontallyraster-scanning the surface of the sample S by using the tip 121.

Although the size of the tip 121 is exaggeratedly shown for convenienceof drawing unlike actual scaling, a Z-direction length of the tip 121may be within a range of several nm to hundreds of nm.

The AFM 100 may include any one of a contact AFM, a force modulusmicroscope (FMM), a lateral force microscope (LFM), a scanningcapacitance microscope (SCM), a scanning thermal microscope (SThM), acontactless AFM, a conductive AFM (CAFM), a dynamic force microscope(DFM), an electrostatic force microscope (EFM), a Kelvin probe forcemicroscope (KPFM), a magnetic force microscope (MFM), a piezoelectricforce microscope (PFM), and a dynamic contact AFM.

The AFM 100 may operate in a contact mode, a contactless mode, and atapping mode. When the AFM 100 operates in the contact mode, a distancebetween the tip 121 and the surface of the sample S may be severalangstroms. At a distance of about several angstroms, a repulsive forceis dominant between the tip 121 and the surface of the sample S. In thecontact mode, a soft tip 121 may be used to prevent damage to the sampleS. In a repulsive force territory, because a change in a force appliedto the tip 121 is large in response to a change in a distance betweenthe tip 121 and the surface of the sample S, the surface of the sample Smay be inspected with a high resolution.

When the AFM 100 operates in the contactless mode, the distance betweenthe tip 121 and the surface of the sample S may be hundreds of angstromsor more. At a distance of about hundreds of angstroms, an attractiveforce is dominant between the tip 121 and the surface of the sample S.In the contactless mode, a hard tip 121 may be used to prevent contactbetween the tip 121 and the surface of the sample S due to theattractive force. A resolution of the contactless mode, is lower thanthat of the contact mode. A scanning speed of the contactless mode, ishigher than that of the contact mode.

In the tapping mode, the tip 121 may vibrate above the sample S to causeonly short intermittent contacts, thereby minimizing damage to thesample S due to the contacts. In a tapping mode operation, constantvibration may be provided to the tip 121 to sense the sample S, therebypreventing damage to the sample S. In addition, the tapping modeoperation may provide the same level of resolution as that in thecontact mode even when a structure having a large height difference isformed on the surface of the sample S.

At least one characterization sample CS for inspecting the probe 120 maybe on the sample support 110. The sample support 110 may support and fixthe sample S and the characterization sample CS. The sample support 110may be a vacuum chuck or an electrostatic chuck. The characterizationsample CS may include a die having a thin film nanostructure formedthereon. The nanostructure may form one or more well-definedcharacterization patterns that may be used to reverse image the tip 121of the probe 120 and thereby determine characteristics of the tip 121,such as tip shape, tip width (e.g., radius), inclination, and the like.

The sample support 110 may include a sample support part 111 supportingthe sample S and a characterization sample support part 115 supportingthe characterization sample CS. The characterization sample support part115 may be on the sample support part 111 but is not limited thereto.The sample support 110 may move the sample S in the X direction, Ydirection, Z direction, or rotate the sample S so that the sample S isscanned by the probe 120.

The X direction and the Y direction are parallel to an upper surface ofthe sample S (i.e., an opposite surface of a lower surface facing thesample support 110). The Z direction is perpendicular to the uppersurface of the sample S. The X direction, the Y direction, and the Zdirection may be substantially perpendicular to one another.

The probe 120 may include a cantilever 125 and the tip 121 connected toan end portion of the cantilever 125. The cantilever 125 may be, forexample, a plate-shaped spring easily bent by a minute force of aboutseveral nanonewtons (nN). An end portion of the tip 121 may be processedto a size of about several atoms by nanotechnology. The resolution ofthe AFM 100 depends on the sharpness of the end portion of the tip 121.

The scanner 130 may scan the sample S by driving the probe 120 in the Xdirection and the Y direction. Although not illustrated, the controller170 may be communicatively connected to the sample support 110.Accordingly, in the alternative, the scanner 130 may scan the sample Sby driving the sample substrate 110 in the X direction and the Ydirection for example. While scanning the sample S, the tip 121 deflectsby an attractive force or a repulsive force from features on the surfaceof the sample S. The deflection of the tip 121 may cause bending of thecantilever 125. The bending of the cantilever 125 may be detected by anoptical lever including the laser device 140 and the photodetector 150.

The laser device 140 generates a laser beam through oscillation. Thelaser beam is radiated on the end portion of the cantilever 125,reflected from the end portion of the cantilever 125, and oriented tothe photodetector 150. The photodetector 150 may include photodiodesdivided into two segments or four segments according to a measurementscheme. The photodetector 150 may amplify and detect a small deflectionof the cantilever 125 by sensing the laser beam.

The controller 170 may precisely control a Z-direction position of thescanner 130 (or sample support 110). For example, the controller 170 maycontrol the scanner 130 (or sample support 110) so that a Z-directiondistance between the tip 121 and the surface of the sample S isconstant. As another example, the controller 170 may control the scanner130 (or sample support 110) so that a force between the tip 121 and thesurface of the sample S is constant.

By scanning the sample S using the scanner 130, information regardingthe sample may be obtained and processed by the processor to generate animage of the sample. For example, the processor 160 may generate atopographic image of the surface of the sample S by storing aZ-direction position of the scanner 130 (or a Z-direction position ofthe probe 120 or sample support 110) according to X-direction andY-direction coordinates on the sample S. An image generated by scanningthe sample S using the scanner 130, such as the topographic image, maybe referred to herein as a “scanned sample image.”

The processor 160 may further generate an image of the shape of the tip121. According to example embodiments, a thickness of the tip 121according to a height from the end portion of the tip 121, and thesharpness of the end portion of the tip 121 may be determined based onan image generated by scanning any one of the sample S and thecharacterization sample CS by using the tip 121.

FIG. 2 is a flowchart for describing a method of operating an AFM,according to example embodiments.

Referring to FIGS. 1 and 2 , the sample S may be inspected in step P10.Inspecting the sample S may include scanning the surface of the sample Sby using the AFM 100 to generate a scanned sample image, as describedabove. An analysis of the scanned sample image may indicate that one ormore abnormalities are present in the scanned sample image. However, itmay be difficult to discern whether the one or more abnormalitiescorrespond to abnormalities present on the surface of sample S orwhether the abnormalities correspond to (i.e., are a result of) a defectin the tip 121 of the probe 120.

The method of operating an AFM as set forth in the flowchart of FIG. 2may be used to discern whether or not one or more abnormalities presentin a scanned sample image correspond to abnormalities present on thesurface of sample S or whether the abnormalities correspond to (i.e.,are a result of) a defect in the tip 121 of the probe 120. For example,if in step P10 it is determined that the scanned sample image isabnormal (e.g., one or abnormalities are present in the scanned sampleimage), the tip 121 may be inspected by using the characterizationsample CS in step P20. Whether the scanned sample image is abnormal maybe determined by comparing the scanned sample image to an image of astandard sample (i.e., “scanned standard sample image”). According toexample embodiments, inspecting the tip 121 by using thecharacterization sample CS may include scanning the characterizationsample CS by using the tip 121.

Hereinafter, the characterization sample CS is described in detail withreference to FIGS. 3A to 5 .

FIG. 3A illustrates a first characterization pattern CP1 of thecharacterization sample CS.

FIG. 3B illustrates an image CPI1 generated by scanning the firstcharacterization pattern CP1 of the characterization sample CS.

FIG. 3C illustrates a damaged tip 121′.

Referring to FIG. 3A, the characterization sample CS may include thefirst characterization pattern CP1. The first characterization patternCP1 may be an concave-convex pattern having a first height H1. Forexample, the first characterization pattern CP1 may be a line and spacepattern of the first height H1. As another example, the firstcharacterization pattern CP1 may include a plurality of holes arrangedin a matrix form in the X direction and the Y direction, each holehaving the first height H1. A planar shape of the plurality of holes maybe any one of a circle, an oval, and a polygon.

According to example embodiments, the tip 121 may be inspected by usingthe first characterization pattern CP1 that recursively appears, anddata of the tip 121 may be statistically processed, thereby improvingthe reliability of the inspection of the tip 121.

According to example embodiments, the first height H1 may be within arange of about 100 nm to about 250 nm. According to example embodiments,the first characterization pattern CPI may be used to determine a widthof the tip 121 at the first height H1 that is relatively high.

Referring to FIGS. 3A and 3B, when the first characterization patternCPI is scanned in a scanning direction SD by using the probe 120, thescanned image CPI1 of FIG. 3B may be generated. Unlike the firstcharacterization pattern CP1, the scanned image CPI1 may includeinclination and corner rounding of an uneven pattern according to theshape of the tip 121.

According to example embodiments, the shape of the tip 121 may bedetermined by deconvolution of the scanned image CPI1. For example, thewidth of the tip 121 at the first height H1 may be obtained by thedeconvolution of the scanned image CPI1.

According to example embodiments, a radius of the end portion of the tip121 may be determined from the radius of curvature of a corner of theuneven pattern appearing in the scanned image CPI1. According to exampleembodiments, inclination of the tip 121 may be determined from theinclination of the uneven pattern of the scanned image CPI1. Accordingto example embodiments, the width of the tip 121 at the first height H1may be determined by comparing a width Wp of the first characterizationpattern CP1 to a width Wm of the scanned image CPI1. For example, thewidth of the tip 121 at the first height H1 may be represented byEquation 1.

Width of the tip 121 at the first height=Wm−Wp  [Equation 1]

Referring to FIG. 3C, when an end portion of the tip 121′ is damaged, atotal height of the tip 121′ is lowered as much as a damaged part RP.Accordingly, a width W1′ of the tip 121′ at the first height H1 afterdamage may be greater than a width W1 of the tip 121′ at the firstheight H1 before the damage. When a width of the uneven pattern formedon the sample (S, see FIG. 1 ) is less than the width W1′ of the tip121′ at the first height H1, the tip 121′ cannot reach an actual bottomsurface of the uneven pattern, and thus, a height of the concave-convexpattern may be wrongly recognized to be lower than an intended height.

Referring back to FIGS. 1 and 3A, when a thickness of the tip 121 of theprobe 120 at the first height H1, which is measured through the firstcharacterization pattern CPI of the characterization sample CS, isgreater than a set value, it may be determined that the tip 121 of theprobe 120 is abnormal.

FIG. 4 illustrates a second characterization pattern CP2 of thecharacterization sample CS.

Referring to FIG. 4 , the second characterization pattern CP2 may be anuneven pattern having a second height H2. For example, the secondcharacterization pattern CP2 may be a line and space pattern of thesecond height H2. As another example, the second characterizationpattern CP2 may include a plurality of holes arranged in the X directionand the Y direction, each hole having the second height H2.

According to example embodiments, the second height H2 may be within arange of about 50 nm to about 150 nm. According to example embodiments,the second characterization pattern CP2 may be used to determine a widthof the tip 121 at the second height H2 that is relatively lower than thefirst height H1 (see FIG. 3 a ). Determining the width of the tip 121 atthe second height H2 is substantially similar to that described withreference to FIGS. 3A to 3C, and thus, a description thereof is notrepeated.

Referring back to FIGS. 1 and 4 , when a thickness of the tip 121 of theprobe 120 at the second height H2, which is measured through the secondcharacterization pattern CP2 of the characterization sample CS, isgreater than a set value, it may be determined that the tip 121 of theprobe 120 is abnormal.

FIG. 5 illustrates a third characterization pattern CP3 of thecharacterization sample CS.

Referring to FIG. 5 , the third characterization pattern CP3 may be anuneven pattern having a third height H3. According to exampleembodiments, the third characterization pattern CP3 may include a roughsurface RS.

According to example embodiments, a root mean square surface roughnessRq of the rough surface RS of the third characterization pattern CP3 maybe within a range of about 0.5 nm to about 1.5 nm. According to exampleembodiments, the root mean square surface roughness Rq of the roughsurface RS of the third characterization pattern CP3 may be about 0.6 nmor more. According to example embodiments, the root mean square surfaceroughness Rq of the rough surface RS of the third characterizationpattern CP3 may be about 0.7 nm or more. According to exampleembodiments, the root mean square surface roughness Rq of the roughsurface RS of the third characterization pattern CP3 may be about 0.8 nmor more. According to example embodiments, the root mean square surfaceroughness Rq of the rough surface RS of the third characterizationpattern CP3 may be about 1.4 nm or less. According to exampleembodiments, the root mean square surface roughness Rq of the roughsurface RS of the third characterization pattern CP3 may be about 1.3 nmor less. According to example embodiments, the root mean square surfaceroughness Rq of the rough surface RS of the third characterizationpattern CP3 may be about 1.2 nm or less. According to exampleembodiments, the root mean square surface roughness Rq of the roughsurface RS of the third characterization pattern CP3 may be about 1.1 nmor less. According to example embodiments, the root mean square surfaceroughness Rq of the rough surface RS of the third characterizationpattern CP3 may be about 1 nm or less.

According to example embodiments, when the root mean square surfaceroughness Rq of the rough surface RS of the third characterizationpattern CP3 is excessively large (e.g., 1.5 nm or more), the end portionof the tip 121 of the probe 120 may be damaged while scanning the thirdcharacterization pattern CP3. According to example embodiments, when theroot mean square surface roughness Rq of the rough surface RS of thethird characterization pattern CP3 is excessively small (e.g., 0.5 nm orless), it is impossible to measure the root mean square surfaceroughness Rq of the rough surface RS even with a good tip 121 of theprobe 120.

When the root mean square surface roughness Rq of the rough surface RSof the third characterization pattern CP3 measured by the probe 120 iswithin a preset range, it may be determined that the end portion of thetip 121 of the probe 120 is not damaged (i.e., sufficiently sharp). Whenthe root mean square surface roughness Rq of the rough surface RS of thethird characterization pattern CP3 measured by the probe 120 is outsideof the preset range, it may be determined that the tip 121 of the probe120 is damaged. For example, when the root mean square surface roughnessRq of the rough surface RS of the third characterization pattern CP3 isabout 0.8 nm, if the root mean square surface roughness Rq of the roughsurface RS measured by the tip 121 of the probe 120 is 1.1 nm or more,or 0.5 nm or less, it may be determined that the end portion of the tip121 of the probe 120 is damaged.

Referring back to FIG. 2 , if it is determined that the tip 121 is good(G) (i.e., not damaged) as the result of inspecting the tip 121 by usingthe characterization sample CS, it may be determined in step P30 that anelement on the sample S is abnormal. For example, it may be determinedthat the one or more abnormalities present in the scanned sample imagegenerated in step P10 correspond to abnormalities on the surface of thesample S.

If it is determined that the tip 121 is not good (NG) (i.e., damaged) asthe result of inspecting the tip 121 by using the characterizationsample CS, the tip 121 may be replaced in step P40. After replacing thetip 121, the sample S may be inspected again in step P10.

According to example embodiments, the aforementioned method of operatingthe AFM 100 may be performed in real-time while inspecting the sample Sby using the AFM 100. Accordingly, it may be prevented that damage tothe tip 121 is wrongly recognized as abnormality of an element and afeature of the sample S, and when damage occurs to the tip 121 whileinspecting the sample S, the tip 121 may be replaced, and thus, thereliability of an operation of the AFM 100 may be improved.Alternatively, the inspection step P20 of the tip 121 may be performedseparately as, for example, a calibration operation prior to inspectingsample S. Accordingly, using the characterization sample CS, adetermination may be made as to whether the tip 121 is good (G) (i.e.,not damaged) or not good (NG) (i.e., damaged) prior to inspecting sampleS.

FIGS. 6A to 6C show changes in a scanned image of the sample S accordingto sharpness of the end portion of the tip 121. Herein, the sharpness ofthe end portion of the tip 121 may be digitized to a radius of the endportion of the tip 121.

More particularly, FIG. 6A shows a scanned image of the sample S whenthe radius of the end portion of the tip 121 is 5 nm, FIG. 6B shows ascanned image of the sample S when the radius of the end portion of thetip 121 is 10 nm, and FIG. 6C shows a scanned image of the sample S whenthe radius of the end portion of the tip 121 is 30 nm.

Referring to FIGS. 1 and 6A to 6C, when the radius of the end portion ofthe tip 121 varies, a scanned image of the same portion of the sample Smay vary. According to example embodiments, the processor 160 maypredict a state (e.g., a shape of the end portion) of the tip 121 from ascanned image of the sample S, based on existing data of the scannedimage of the sample S. The controller 170 may generate a control signalfor scanning only an appropriate portion of the characterization sampleCS in response to the prediction of the processor 160. Accordingly, atime taken to inspect the tip 121 may be reduced, and a turnaround timefor inspection using the AFM 100 may be reduced.

As another example, the shape of the tip 121 may be obtained with highprecision by scanning all patterns of the characterization sample CS bythe tip 121.

FIG. 7 is a flowchart for describing a method of manufacturing asemiconductor device, according to example embodiments.

FIGS. 8A, 8B, 9A, 9B, 10A, 10B, and 11 to 14 are top views andcross-sectional views for describing the method of manufacturing asemiconductor device, according to example embodiments.

More particularly, FIGS. 8A, 9A, and 10A are layout diagrams of astructure formed on a wafer (substrate) 300 according to the progress ofa process. FIG. 8B shows cross-sectional views taken along line 8A-8A′and line 8B-8B′ of FIG. 8A. FIG. 9B shows cross-sectional views takenalong line 9A-9A′ and line 9B-9B′ of FIG. 9A. FIG. 10B showscross-sectional views taken along line 10A-10A′ and line 10B-10B′ ofFIG. 10A.

FIGS. 11 to 20 are cross-sectional views illustrating changes of partscorresponding to FIG. 10B according to the progress of a process.

According to some embodiments, FIGS. 7 to 14 may illustrate a method ofmanufacturing a dynamic random access memory (DRAM) device including aburied cell array transistor (BCAT).

Referring to FIGS. 7, 8A, and 8B, a plurality of active patterns 305 anda device isolation trench IST may be formed in step P110. According toexample embodiments, the plurality of active patterns 305 and the deviceisolation trench IST may be formed by etching an upper part of asubstrate 300. The device isolation trench IST may be a space betweenthe plurality of active patterns 305 formed by an anisotropic etchingprocess. The plurality of active patterns 305 may extend in a directionthat is oblique with respect to the X direction and the Y direction andbe aligned along rows and columns.

The substrate 300 may include or may be formed of, for example, silicon,germanium, silicon-germanium, or a group III-V compound, such as galliumphosphide (GaP), gallium arsenide (GaAs), or gallium antimonide (GaSb).

According to example embodiments, a depth of the device isolation trenchIST may be within a range of about 100 nm to about 250 nm. Herein, thedepth of the device isolation trench IST may be a Z-direction distancebetween a bottom surface of the device isolation trench IST and an uppersurface of each of the plurality of active patterns 305.

According to example embodiments, a width of the device isolation trenchIST may be within a range of about 30 nm to about 100 nm. Herein, thewidth of the device isolation trench IST may be a horizontal distance(i.e., an X-direction distance and/or a Y-direction distance) betweenadjacent two of the plurality of active patterns 305.

Next, referring to FIGS. 1, 7, and 8B, the device isolation trench ISTmay be inspected in step P120. The device isolation trench IST may beinspected by using the AFM 100. Inspecting the device isolation trenchIST may include inspecting the depth of the device isolation trench IST.The AFM 100 may inspect the device isolation trench IST by scanning thesubstrate 300, in which the device isolation trench IST is formed, inthe X direction and the Y direction.

When the depth of the device isolation trench IST is excessively small,a characteristic of the BCAT may degrade, and a short-circuit may occurin that neighboring active patterns 305 are not separated from eachother.

Inspecting the device isolation trench IST may be performed by themethod of inspecting a sample S, which has been described with referenceto FIG. 2 . More particularly, the depth of the device isolation trenchIST in the substrate 300 may be inspected by using the AFM 100, and ifthe depth of the device isolation trench IST is abnormal, the tip 121may be inspected by using the characterization sample CS. If the tip 121is normal, it may be determined that a process of forming the deviceisolation trench IST is faulty. If the tip 121 is abnormal, the probe120 may be replaced, and then, the depth of the device isolation trenchIST may be inspected again.

Inspecting the tip 121 may include measuring a width of the tip 121 atthe first height H1 by using the first characterization pattern (CP1,see FIG. 3A) of the characterization sample CS. However, the inventiveconcept is not limited thereto, and the tip 121 may be inspected byusing the second and third characterization patterns (CP2 and CP3, seeFIGS. 4 and 5 ).

Next, referring to FIGS. 1, 9A, and 9B, a device isolation layer 302 maybe formed in step P130. The device isolation layer 302 may be formed bysufficiently providing an insulating layer including silicon oxide tofill the device isolation trench IST and planarizing an upper part ofthe insulating layer by a chemical mechanical polishing (CMP) process orthe like so that an upper surface of the active pattern 305 is exposed.The series of operations P110, P120, and P130 may be called a shallowtrench isolation (STI) process.

By forming the device isolation layer 302, adjacent two of the pluralityof active patterns 305 may be separated from each other with the deviceisolation layer 302 therebetween. An upper surface of the deviceisolation layer 302 may be coplanar with upper surfaces of the pluralityof active patterns 305. A part where an upper surface of the substrate300 is covered by the device isolation layer 302 may be called a fieldarea, and a part where the upper surfaces of the plurality of activepatterns 305 are exposed may be called an active area.

Next, referring to FIGS. 7, 10A, and 10B, gate trenches GT may be formedby etching an upper part of each active pattern 305 and/or an upper partof the device isolation layer 302 in step P140.

According to some embodiments, a hard mask (not shown) partiallyexposing therethrough an upper surface of each active pattern 305 and anupper surface of the device isolation layer 302 may be formed, and then,each active pattern 305 and the device isolation layer 302 may bepartially etched by using the hard mask, thereby forming the gatetrenches GT.

According to some embodiments, the gate trench GT may extend in the Ydirection. The gate trench GT may penetrate into an upper part of eachactive pattern 305 and the device isolation layer 302 in the Zdirection. According to some embodiments, the gate trenches GT may beseparated from each other in a first direction (the X direction).

According to some embodiments, each active pattern 305 may horizontallyintersect with two gate trenches GT. An upper part of each activepattern 305 may be divided into a center part 305C and two edge parts305E separated from each other with the center part 305C therebetween bytwo gate trenches GT.

Next, referring to FIGS. 7 and 11 , a dielectric material layer 322L maybe formed in step P150.

For example, the dielectric material layer 322L may be formed by athermal oxidation process on a surface of the active pattern 305 exposedby the gate trench GT. As another example, the dielectric material layer322L may be formed by depositing silicon oxide or metal oxide on thesurface of the active pattern 305 by, for example, a chemical vapordeposition (CVD) process or the like.

Next, referring to FIGS. 1, 7, and 11 , the dielectric material layer322L may be inspected in step P160. The dielectric material layer 322Lmay be inspected by using the AFM 100. Inspecting the dielectricmaterial layer 322L may include measuring roughness of an upper surfaceof the dielectric material layer 322L. The AFM 100 may inspect thedielectric material layer 322L by scanning the substrate 300, on whichthe dielectric material layer 322L is formed, in the X direction and theY direction. According to example embodiments, in step P160, a part ofthe dielectric material layer 322L on the active pattern 305 and thedevice isolation layer 302 may be inspected. According to exampleembodiments, in step P160, a part of the dielectric material layer 322Lin the gate trench GT may not be inspected.

When the roughness of the dielectric material layer 322L is outside of acertain range, electrical characteristics of a gate electrode (320, seeFIG. 14 ) to be subsequently formed may degrade.

Inspecting the dielectric material layer 322L may be performed by themethod of inspecting a sample S, which has been described with referenceto FIG. 2 . More particularly, the roughness of the dielectric materiallayer 322L may be inspected by using the AFM 100, and if the roughnessof the dielectric material layer 322L is abnormal, the tip 121 may beinspected by using the characterization sample CS. If the tip 121 isnormal, it may be determined that a process of forming the dielectricmaterial layer 322L is faulty. If the tip 121 is abnormal, the probe 120may be replaced, and then, the roughness of the dielectric materiallayer 322L may be inspected again.

Inspecting the tip 121 may include measuring the sharpness of the tip121 by using the third characterization pattern (CP3, see FIG. 5 ) ofthe characterization sample CS. However, the inventive concept is notlimited thereto, and the tip 121 may be inspected by using the first andsecond characterization patterns (CP1 and CP2, see FIGS. 3A and 4 ).

Next, referring to FIGS. 7 and 12 , a gate conductive material layer324L may be formed in step P170.

The gate conductive material layer 324L may fill a remaining portion ofthe gate trench GT on the dielectric material layer 322L. The gateconductive material layer 324L may be formed by, for example, an atomiclayer deposition (ALD) process, a sputtering process, or the like usinga metal and/or metal nitride. The gate conductive material layer 324Lmay include or may be formed of, for example, a material having a goodstep coverage, such as tungsten (W).

Next, referring to FIGS. 7, 12, and 13 , a gate dielectric pattern 322and a gate conductive pattern 324 may be formed in step P180.

The gate dielectric pattern 322 and the gate conductive pattern 324 maybe formed by planarizing the dielectric material layer 322L and the gateconductive material layer 324L through a CMP process so that the uppersurface of the active pattern 305 is exposed and removing, through anetching process, a portion of the dielectric material layer 322L and thegate conductive material layer 324L formed inside the gate trench GT.The gate dielectric pattern 322 and the gate conductive pattern 324 mayfill a lower part of the gate trench GT.

Next, the gate conductive pattern 324 may be inspected in step P190.

The gate conductive pattern 324 may be inspected by using the AFM 100.Inspecting the gate conductive pattern 324 may include measuring theroughness of an upper surface of the gate conductive pattern 324. As anon-limiting example, the roughness of the upper surface of the gateconductive pattern 324 may be measured by scanning, by using the AFM100, an inspection mark formed outside a device area shown in FIG. 13 .

The inspection mark may be formed on, for example, a scribe lane that isa region for separating a plurality of chips formed on the substrate300. The inspection mark may include the same material as the gateconductive pattern 324. The inspection mark may be formed by the sameprocess as a process of forming the gate conductive pattern 324. Theinspection mark may be formed substantially at the same time as the gateconductive pattern 324 is formed.

A grain size of a conductive material constituting the gate conductivepattern 324 may be determined from the roughness of the upper surface ofthe gate conductive pattern 324. That is, electrical characteristics ofthe gate conductive pattern 324 may be determined by inspecting theroughness of the upper surface of the gate conductive pattern 324.

Inspecting the gate conductive pattern 324 may be performed by themethod of inspecting a sample S, which has been described with referenceto FIG. 2 . More particularly, the roughness of the inspection mark formeasuring the roughness of the upper surface of the gate conductivepattern 324 above the substrate 300 may be measured by using the AFM100, and if the roughness of the inspection mark is out of a set range,the tip 121 may be inspected by using the characterization sample CS.

If the tip 121 is normal, it may be determined that a process of formingthe gate conductive pattern 324 is faulty. If the tip 121 is abnormal,the probe 120 may be replaced, and then, the roughness of the inspectionmark may be measured again.

Inspecting the tip 121 may include measuring the sharpness of the tip121 by using the third characterization pattern (CP3, see FIG. 5 ) ofthe characterization sample CS. However, the inventive concept is notlimited thereto, and the tip 121 may be inspected by using the first andsecond characterization patterns (CP1, CP2, see FIGS. 3A and 4 ).

Next, referring to FIGS. 7 and 14 , a gate mask 326 may be formed instep P200.

A mask layer filling a remaining portion of the gate trench GT may beformed on the gate dielectric pattern 322 and the gate conductivepattern 324, and then, the gate mask 326 may be formed by planarizing anupper part of the mask layer so that the upper surface of the activepattern 305 is exposed. According to some embodiments, the mask layermay be formed by a CVD process and include silicon nitride.

Accordingly, a word line structure 320 including a conformal gatedielectric pattern 322 covering the lower part of the gate trench GT,the gate conductive pattern 324 filling a space defined by the gatedielectric pattern 322, and the gate mask 326 covering the gatedielectric pattern 322 and the gate conductive pattern 324 and fillingan upper part of the gate trench (GT, see FIG. 10A) may be formed.

According to an arrangement of the gate trenches (GT, see FIG. 10A), aplurality of word line structures 320 extending in the Y direction maybe formed by being separated from each other and aligned in the firstdirection (the X direction). Each of the plurality of word linestructures 320 may be buried in the active pattern 305. As describedabove, the upper part of the active pattern 305 may be divided into thecenter part (305C, see FIG. 10B) between two word line structures 320and the edge parts (305E, see FIG. 10B) separated from the center part(305C, see FIG. 10B) with each of plurality of word line structures 320therebetween.

Next, a first impurity region 301 and a second impurity region 303 maybe formed by performing an ion injection process on the upper part ofthe active pattern 305 adjacent to the plurality of word line structures320. According to some embodiments, the first impurity region 301 may beformed at the center part (305C, see FIG. 10B) of the active pattern305, and the second impurity region 303 may be formed at the edge parts(305E, see FIG. 10B) of the active pattern 305.

Next, referring to FIGS. 7 and 15 , a capping layer 330 and a firstinterlayer insulating layer 340 may be formed in step P210.

The capping layer 330 covering the active pattern 305 and the deviceisolation layer 302 may be formed, and the first interlayer insulatinglayer 340 may be formed on the capping layer 330. According to someembodiments, the capping layer 330 and the first interlayer insulatinglayer 340 may include or may be formed of silicon nitride and siliconoxide, respectively. The capping layer 330 may function as an etchingstop layer, which protects the active pattern 305 or the first andsecond impurity regions 301 and 303 in subsequent etching processes.

Next, referring to FIGS. 7 and 16 , a groove GR may be formed in stepP220.

The groove GR may penetrate through the first interlayer insulatinglayer 340 and the capping layer 330 in the Z direction and expose anupper surface of the first impurity region 301. The groove GR may extendin a direction (the X direction of FIG. 10A) that is perpendicular to anextension direction of the gate electrode 320. Grooves GR may beseparated from each other in the Y direction (see FIG. 10A). A width ofthe groove GR in the Y direction (see FIG. 10A) may be within a range ofabout 10 nm to about 100 nm. A depth of the groove GR may be within arange of about 50 nm to about 150 nm.

According to some embodiments, a portion of the first impurity region301 may be removed by an etching process of forming the groove GR.Accordingly, a level difference may occur between the first and secondimpurity regions 301 and 303, and a bridge or short circuit between abit line structure (350, see FIG. 18 ) and a conductive contact (370,see FIG. 20 ) formed in subsequent processes may be prevented.

Next, referring to FIGS. 1, 7, and 16 , the groove GR may be inspectedin step P230.

The groove GR may be inspected by using the AFM 100. Inspecting thegroove GR may include inspecting the depth of the groove GR. The AFM 100may inspect the groove GR by scanning the substrate 300, above which thegroove GR is formed, in the X direction and the Y direction.

When the depth of the groove GR is excessively small, there may occur anopen fault that an upper surface of the first impurity region 301 is notexposed by the groove GR. When the depth of the groove GR is excessivelylarge, an operation characteristic of the BCAT may degrade.

Inspecting the groove GR may be performed by the method of inspecting asample S, which has been described with reference to FIG. 2 . Moreparticularly, the depth of the groove GR above the substrate 300 may beinspected by using the AFM 100, and if the depth of the groove GR isabnormal, the tip 121 may be inspected by using the characterizationsample CS. If the tip 121 is normal, it may be determined that a processof forming the groove GR is faulty. If the tip 121 is abnormal, theprobe 120 may be replaced, and then, the depth of the groove GR may beinspected again.

Inspecting the tip 121 may include measuring a width of the tip 121 atthe second height H2 by using the second characterization pattern (CP2,see FIG. 4 ) of the characterization sample CS. However, the inventiveconcept is not limited thereto, and the tip 121 may be inspected byusing the first and third characterization patterns (CP1 and CP3, seeFIGS. 3A and 5 ).

Next, referring to FIGS. 7, 17 and 18 , the bit line structure 350 maybe formed in step P240.

More particularly, referring to FIG. 17 , a first conductive layer 351Lfilling the groove (GR, see FIG. 16 ) may be formed on the firstinterlayer insulating layer 340. A barrier conductive layer 353L and asecond conductive layer 355L may be formed on the first conductive layer351L. A mask pattern 357 may be formed on the second conductive layer355L.

According to some embodiments, the first conductive layer 351L mayinclude or may be formed of doped polysilicon. According to someembodiments, the barrier conductive layer 353L may include or may beformed of metal nitride or metal silicide nitride. According to someembodiments, the second conductive layer 355L may include or may beformed of a metal material. According to some embodiments, the firstconductive layer 351L, the barrier conductive layer 353L, and the secondconductive layer 355L may be formed by a sputtering process, a physicalvapor deposition (PVD) process, an ALD process, or the like.

The mask pattern 357 may include silicon nitride and have a line shapeextending in the X direction (see FIG. 10A). According to someembodiments, a width (e.g., a width in the first direction) of the maskpattern 357 may be less than a width of the groove GR.

Referring to FIGS. 17 and 18 , the second conductive layer 355L, thebarrier conductive layer 353L, and the first conductive layer 351L maybe etched by using the mask pattern 357 as an etching mask. Accordingly,a first conductive pattern 351, a barrier conductive pattern 353, and asecond conductive pattern 355 sequentially stacked on the first impurityregion 301 may be formed.

The first conductive pattern 351, the barrier conductive pattern 353,the second conductive pattern 355, and the mask pattern 357 mayconstitute the bit line structure 350. The bit line structure 350 mayextend in the Y direction (see FG. 10A) on the first impurity region301. According to some embodiments, the bit line structure 350 may havea less width than the groove (GR, see FIG. 16 ). Therefore, a side wallof the bit line structure 350 may be separated from a side wall of thegroove (GR, see FIG. 16 ).

Referring to FIG. 19 , a spacer 358 may be formed on the side wall ofthe bit line structure 350. The spacer 358 may include or may be formedof silicon nitride. According to example embodiments, a conformalmaterial layer covering the bit line structure 350 may be formed on thefirst interlayer insulating layer 340, and the spacer 358 may be formedby anisotropically etching the material layer.

Next, a second interlayer insulating layer 360 covering the bit linestructure 350 may be formed on the first interlayer insulating layer340. According to some embodiments, the second interlayer insulatinglayer 360 may fill a remaining portion of the groove (GR, see FIG. 16 ),which is not filled with the bit line structure 350.

According to some embodiments, an upper part of the second interlayerinsulating layer 360 may be planarized by a CMP process to expose anupper surface of the mask pattern 357. According to some embodiments,similarly to the first interlayer insulating layer 340, the secondinterlayer insulating layer 360 may include or may be formed of siliconoxide.

Next, referring to FIG. 20 , conductive contacts 370 each connected tothe second impurity region 303 by penetrating through the secondinterlayer insulating layer 360, the first interlayer insulating layer340, and the capping layer 330 may be formed. The conductive contacts370 may have a pillar shape extending in a vertical direction (i.e., theZ direction). The conductive contacts 370 may include or may be formedof, for example, a metal, such as copper, W, or aluminum, or aconductive material, such as metal nitride, doped polysilicon, or metalsilicide.

According to some embodiments, the conductive contacts 370 may be formedby forming contact holes penetrating into the second impurity region303, providing a conductive material layer to fill the contact holesthrough an ALD process, a CVD process, a sputtering process, or thelike, and then planarizing an upper part of the conductive materiallayer through a CMP process so that the upper surface of the maskpattern 357 is exposed. According to some embodiments, a barrierconductive layer including titanium, titanium nitride, or the like maybe further provided between the conductive contacts 370 and the secondinterlayer insulating layer 360.

Next, a DRAM including the BCAT may be provided by sequentiallyperforming a storage node forming process and a plate electrode formingprocess.

While the inventive concept has been particularly shown and describedwith reference to embodiments thereof, it will be understood thatvarious changes in form and details may be made therein withoutdeparting from the spirit and scope of the following claims.

What is claimed is:
 1. A method of operating an atomic force microscope(AFM), the method comprising: inspecting a sample by using the AFM; andinspecting a tip of a probe of the AFM by using a characterizationsample, wherein the characterization sample comprises: a firstcharacterization pattern that includes a line and space pattern of afirst height; a second characterization pattern that includes a line andspace pattern of a second height that is lower than the first height;and a third characterization pattern that includes a line and spacepattern of a third height that is lower than the second height, andincludes a rough surface.
 2. The method of claim 1, wherein the firstheight is within a range of 100 nm to 250 nm.
 3. The method of claim 1,wherein the second height is within a range of 50 nm to 150 nm.
 4. Themethod of claim 1, wherein a root mean square surface roughness of therough surface of the third characterization pattern is within a range of0.5 nm to 1.5 nm.
 5. The method of claim 1, wherein the firstcharacterization pattern is used to measure a width of the tip at thefirst height, and the second characterization pattern is used to measurea width of the tip at the second height.
 6. The method of claim 1,wherein the third characterization pattern is used to measure asharpness of the tip.
 7. The method of claim 1, wherein inspecting thetip comprises scanning only some selected from among the first to thirdcharacterization patterns, based on an inspection result of the sample.8. The method of claim 1, wherein inspecting the tip comprisessequentially scanning the first to third characterization patterns.
 9. Amethod of operating an atomic force microscope (AFM), the methodcomprising: inspecting a sample by using the AFM; generating, based onthe inspecting, a scanned sample image including one or moreabnormalities; inspecting a tip of a probe of the AFM by using acharacterization sample to determine if the tip is normal or abnormal;determining that the sample is abnormal if the tip of the AFM isdetermined to be normal; and replacing the tip of the AFM if the tip ofthe AFM is determined to be abnormal.
 10. The method of claim 9, whereinthe characterization sample comprises: a first characterization samplethat includes a line and space pattern having a height of 100 nm to 250nm; and a second characterization sample that includes a line and spacepattern having a height of 50 nm to 150 nm.
 11. The method of claim 10,wherein the characterization sample further comprises a thirdcharacterization pattern that includes a rough surface.
 12. The methodof claim 11, wherein a root mean square surface roughness of the roughsurface of the third characterization pattern is within a range of 0.5nm to 1.5 nm.
 13. A method of manufacturing a semiconductor device, themethod comprising: forming active patterns separated from each other ona substrate and a device isolation trench that is a space between theactive patterns, by anisotropically etching the substrate; forming adevice isolation layer in the device isolation trench; forming gatetrenches separated from each other in a first direction that is parallelto an upper surface of the substrate, extending in a second directionthat is parallel to the upper surface of the substrate and perpendicularto the first direction, and partially penetrating into the deviceisolation layer and the active patterns; forming a dielectric materiallayer partially filling the gate trench; forming a gate conductivematerial layer filling the gate trench; forming a gate conductivepattern in the gate trench by planarizing the dielectric material layerand the gate conductive material layer; forming a gate mask on the gateconductive pattern; forming first impurity regions and second impurityregions by doping upper parts of the active patterns; forming a cappinglayer and a first interlayer insulating layer covering the gate mask,the first impurity regions, and the second impurity regions; etching thecapping layer and the first interlayer insulating layer to form a groovethrough which the first impurity regions are exposed; inspecting any oneof the device isolation trench, the dielectric material layer, the gateconductive pattern, and the groove by using an atomic force microscope(AFM); inspecting a tip of a probe of the AFM by using acharacterization sample to determine if the tip is normal or abnormal;and determining that any one of the device isolation trench, thedielectric material layer, the gate conductive pattern, and the grooveis abnormal, based in part on whether the tip is determined to benormal.
 14. The method of claim 13, wherein the characterization samplecomprises: a first characterization pattern that includes a line andspace pattern of a first height; a second characterization pattern thatincludes a line and space pattern of a second height that is lower thanthe first height; and a third characterization pattern that includes arough surface.
 15. The method of claim 14, wherein the first height iswithin a range of 100 nm to 250 nm, and the second height is within arange of 50 nm to 150 nm.
 16. The method of claim 14, wherein a rootmean square surface roughness of the rough surface of the thirdcharacterization pattern is within a range of 0.5 nm to 1.5 nm.
 17. Themethod of claim 14, wherein inspecting the device isolation trenchcomprises: scanning the device isolation trench by using the tip; andmeasuring a width of the tip at the first height by using the firstcharacterization pattern.
 18. The method of claim 14, wherein theinspecting the dielectric material layer comprises: scanning thedielectric material layer by using the tip; and measuring a sharpness ofthe tip by using the third characterization pattern.
 19. The method ofclaim 14, wherein, when forming the gate conductive pattern, aninspection pattern including the same material as the gate conductivematerial layer is simultaneously formed, and inspecting the gateconductive pattern comprises: scanning the inspection pattern by usingthe tip; and measuring a sharpness of the tip by using the thirdcharacterization pattern.
 20. The method of claim 14, wherein inspectingthe groove comprises: scanning the groove by using the tip; andmeasuring a width of the tip at the second height by using the secondcharacterization pattern.